In this study, we investigated the performance of an
immobilized β-galactosidase inclusion bodies-containing
Escherichia coli cell reactor, where the cells were immobilized
in alginate beads, which were then used in repeated-batch
operations for the hydrolysis of o-nitrophenyl-β-D-galactoside
or lactose over the long-term. In particular, in the Tris
buffer system, disintegration of the alginate beads was not
observed during the operation, which was observed for
the phosphate buffer system. The o-nitrophenyl-β-Dgalactoside
hydrolysis was operated successfully up to about
80 h, and the runs were successfully repeated at least eight
times. In addition, hydrolysis of lactose was successfully
carried out up to 240 h. Using Western blotting analyses,
it was verified that the β-galactosidase inclusion bodies
were sustained in the alginate beads during the repeatedbatch
operations. Consequently, we experimentally verified
that β-galactosidase inclusion bodies-containing Escherichia
coli cells could be used in a repeated-batch reactor as a
biocatalyst for the hydrolysis of o-nitrophenyl-β-D-galactoside
or lactose. It is probable that this approach can be applied
to enzymatic synthesis reactions for other biotechnology
applications, particularly reactions that require long-term
and stable operation.